In this talk I will introduce hexagonal boron nitride (hBN) as a promising layered material that hosts ultra-bright quantum emitters. I will present several avenues to engineer these emitters in different forms of hBN hosts and then show unique tuning experiments and promising results for controlling the emission wavelength of these quantum emitters.
At the second part of my talk, I will discuss promising avenues to integrate the emitters with plasmonic and photonic cavities to achieve improved collection efficiency and Purcell enhancement. Lastly, I will introduce the fabrication and characterization of monolithic hBN cavities.
In this work we couple bright room-temperature single-photon emission from a hexagonal boron nitride atomic defect into a laser-written photonic chip. We perform single photon state manipulation with evanescently coupled waveguides acting as a multiple beam splitter, and generate a superposition state maintaining single photon purity. We demonstrate that such states can be utilized for quantum random number generation.
Quantum optical information systems offer the potential for secure communication and fast quantum computation. To fully characterise a quantum optical system one has to use quantum tomography.1 The integration of quantum optics onto photonic chips provides advantages such as miniaturisation and stability, significantly improving quantum tomography using both re-configurable, and more recently, simpler static designs. These on-chip designs have, so far, only used probabilistic single photon sources. Here we are working towards quantum tomography using a true deterministic source - an InGaAs quantum dot.
The fundamental study and realisation of practical devices for quantum nanophotonic systems stems from the development of hybridised devices, consisting of a single photon source and various other constituents, which aid in controlling light-matter interactions. Emitters hosted within hexagonal boron nitride (hBN) are such a source favoured for this role, owing to its high quantum efficiency, brightness, and robustness. In our work, we explore and demonstrate the integration of hBN emitters with plasmonics, in two distinct arrangements – gold nanospheres, and a gold plasmonic nanocavity array. The former involves the utilisation of an atomic force microscope (AFM) tip to precisely position gold nanospheres to within close proximity to the quantum emitters and observe the resulting emission enhancement and fluorescence lifetime reduction. A fluorescence enhancement of over 300% and a saturated count rate in excess of 5M counts/sec is achieved, emphasising the potential of this material for hybridisation. The latter arrangement involves the direct transfer of a gold plasmonic lattice on top of an emitter hosted within hBN, similarly, to achieve emission enhancement as well as a reduction in fluorescence lifetime and provides an approach for achieving scalable, integrated hybrid systems based on low-loss plasmonic nanoparticle arrays. Both these systems give promising solutions for future employment of quantum emitters in hBN for integrated nanophotonic devices and provide us insight into the complex photodynamics, which envelop the emitters hosted within the material.
Efficient extraction of photons from quantum emitters is an important prerequisite for the use of such emitters in quantum optical applications as single photons sources or sensors. One way to achieve this is by coupling to a suited photonics structure, which guides away the emitter light. Here, we show the coupling of a single defect in hexagonal boron nitride (hBN) to a tapered optical fiber via a nanomanipulation technique [1]. Defects in hBN are capable of emitting single photons at room temperature while being photostable at the same time – two properties that make them ideal candidates for integration in single photon sources. The high control the manipulation technique provides avoids covering the whole nanofiber with emitters. We characterize the coupled system in terms of achievable count rates, saturation intensity, and spectral properties. Antibunching measurements are used to proof the single emitter nature of the defect. Our results pave the way for integration of single defects in hBN into photonic structure and their use as single photon sources in quantum optical applications such as quantum crypthography.
[1] A W Schell et al., ACS Photonics, 4, 761–767 (2017)
Among the quantum systems capable of emitting single photons, the class of recently discovered defects in hexagonal boron nitride (hBN) is especially interesting, as these defects offer much desired characteristics such as narrow emission lines and photostability. Like for any new class of quantum emitters, the first challenges to solve are the understanding of their photophysics as well as to find ways to facilitate integration in photonics structures. Here, we will show our investigation of the optical transition in hBN with different methods: Employing excitation with a short laser pulse the emission properties in case of linear and non-linear excitation can be compared [1]. The possibility to perform two-photon excitation makes this single photon emitter an interesting candidate as a biosensor. We further show the behaviour of defects in hBN when being excited with different wavelengths and deduce the consequences for its level scheme. Here, it is found that the quantum efficiency of the emitters varies strongly with excitation wavelength, a strong indication of a branched level system with different decay pathways.
[1] A W Schell et al., APL Photonics 1, 091302 (2016)
[2] A W Schell et al., arXiv:1706.08303 (2017)
Efficient extraction of photons from quantum emitters is an important prerequisite for the use of such emitters in quantum optical applications as single photons sources or sensors. One way to achieve this is by coupling to a suited photonics structure, which guides away the emitter light. Here, we show the coupling of a single defect in hexagonal boron nitride (hBN) to a tapered optical fiber via a nanomanipulation technique. Defects in hBN are capable of emitting single photons at room temperature while being photostable at the same time – two properties that make them ideal candidates for integration in single photon sources. The high control the manipulation technique provides avoids covering the whole nanofiber with emitters. We characterize the coupled system in terms of achievable count rates, saturation intensity, and spectral properties. Antibunching measurements are used to proof the single emitter nature of the defect. Our results pave the way for integration of single defects in hBN into photonic structure and their use as single photon sources in quantum optical applications such as quantum crypthography.
Recently, two-dimensional materials have gained much interest for various applications in nanophotonics and quantum optics, as they possess a strong luminescence and are able to host single quantum emitters. Excitation of quantum emitters via a two-photon process can be employed for high resolution imaging and has applications in quantum optics. Here, we present one- and two-photon excitation of single defects in hexagonal boron nitride (hBN) and analyse the properties of the emitted light [1]. We find clear antibunching signals that prove the single emitter character in both excitation cases. To gain further knowledge, we also obtain saturation curves. From a comparison of one- and two-photon case insights about the level structure of the defects can be obtained. These results will not only help the fundamental understanding of defects in hBN, but also help to introduce this class of emitters in optical imaging, as the defects in hBN are of small spatial extend, photostable and emit their fluorescence well in the wavelength region of the biological optical window.
[1] A. W. Schell et al. arXiv:1606.09364 (2016)
Bio-imaging requires robust ultra-bright probes without causing any toxicity to the cellular environment, maintain their
stability and are chemically inert. In this work we present hexagonal boron nitride (hBN) nanoflakes which exhibit
narrowband ultra-bright single photon emitters1. The emitters are optically stable at room temperature and under ambient
environment. hBN has also been noted to be noncytotoxic and seen significant advances in functionalization with
biomolecules2,3. We further demonstrate two methods of engineering this new range of extremely robust multicolour
emitters across the visible and near infrared spectral ranges for large scale sensing and biolabeling applications.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.